complete the sys/netbt import and adopt some more code to our interfaces

1 files changed, 1690 insertions, 0 deletions

diff --git a/sys/netbt/rfcomm_session.c b/sys/netbt/rfcomm_session.c
new file mode 100644
index 00000000000..f1d88643f54
--- /dev/null
+++ b/sys/netbt/rfcomm_session.c
@@ -0,0 +1,1690 @@
+/*	$OpenBSD: rfcomm_session.c,v 1.1 2007/06/01 02:46:12 uwe Exp $	*/
+/*	$NetBSD: rfcomm_session.c,v 1.9 2007/04/21 06:15:23 plunky Exp $	*/
+
+/*-
+ * Copyright (c) 2006 Itronix Inc.
+ * All rights reserved.
+ *
+ * Written by Iain Hibbert for Itronix Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of Itronix Inc. may not be used to endorse
+ *    or promote products derived from this software without specific
+ *    prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL ITRONIX INC. BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/mbuf.h>
+#include <sys/proc.h>
+#include <sys/systm.h>
+#include <sys/types.h>
+
+#include <netbt/bluetooth.h>
+#include <netbt/hci.h>
+#include <netbt/l2cap.h>
+#include <netbt/rfcomm.h>
+
+/******************************************************************************
+ *
+ * RFCOMM Multiplexer Sessions sit directly on L2CAP channels, and can
+ * multiplex up to 30 incoming and 30 outgoing connections.
+ * Only one Multiplexer is allowed between any two devices.
+ */
+
+static void rfcomm_session_timeout(void *);
+static void rfcomm_session_recv_sabm(struct rfcomm_session *, int);
+static void rfcomm_session_recv_disc(struct rfcomm_session *, int);
+static void rfcomm_session_recv_ua(struct rfcomm_session *, int);
+static void rfcomm_session_recv_dm(struct rfcomm_session *, int);
+static void rfcomm_session_recv_uih(struct rfcomm_session *, int, int, struct mbuf *, int);
+static void rfcomm_session_recv_mcc(struct rfcomm_session *, struct mbuf *);
+static void rfcomm_session_recv_mcc_test(struct rfcomm_session *, int, struct mbuf *);
+static void rfcomm_session_recv_mcc_fcon(struct rfcomm_session *, int);
+static void rfcomm_session_recv_mcc_fcoff(struct rfcomm_session *, int);
+static void rfcomm_session_recv_mcc_msc(struct rfcomm_session *, int, struct mbuf *);
+static void rfcomm_session_recv_mcc_rpn(struct rfcomm_session *, int, struct mbuf *);
+static void rfcomm_session_recv_mcc_rls(struct rfcomm_session *, int, struct mbuf *);
+static void rfcomm_session_recv_mcc_pn(struct rfcomm_session *, int, struct mbuf *);
+static void rfcomm_session_recv_mcc_nsc(struct rfcomm_session *, int, struct mbuf *);
+
+/* L2CAP callbacks */
+static void rfcomm_session_connecting(void *);
+static void rfcomm_session_connected(void *);
+static void rfcomm_session_disconnected(void *, int);
+static void *rfcomm_session_newconn(void *, struct sockaddr_bt *, struct sockaddr_bt *);
+static void rfcomm_session_complete(void *, int);
+static void rfcomm_session_linkmode(void *, int);
+static void rfcomm_session_input(void *, struct mbuf *);
+
+static const struct btproto rfcomm_session_proto = {
+	rfcomm_session_connecting,
+	rfcomm_session_connected,
+	rfcomm_session_disconnected,
+	rfcomm_session_newconn,
+	rfcomm_session_complete,
+	rfcomm_session_linkmode,
+	rfcomm_session_input,
+};
+
+struct rfcomm_session_list
+	rfcomm_session_active = LIST_HEAD_INITIALIZER(rfcomm_session_active);
+
+struct rfcomm_session_list
+	rfcomm_session_listen = LIST_HEAD_INITIALIZER(rfcomm_session_listen);
+
+struct pool rfcomm_credit_pool;
+
+/*
+ * RFCOMM System Parameters (see section 5.3)
+ */
+int rfcomm_mtu_default = 127;	/* bytes */
+int rfcomm_ack_timeout = 20;	/* seconds */
+int rfcomm_mcc_timeout = 20;	/* seconds */
+
+/*
+ * Reversed CRC table as per TS 07.10 Annex B.3.5
+ */
+static const uint8_t crctable[256] = {	/* reversed, 8-bit, poly=0x07 */
+	0x00, 0x91, 0xe3, 0x72, 0x07, 0x96, 0xe4, 0x75,
+	0x0e, 0x9f, 0xed, 0x7c, 0x09, 0x98, 0xea, 0x7b,
+	0x1c, 0x8d, 0xff, 0x6e, 0x1b, 0x8a, 0xf8, 0x69,
+	0x12, 0x83, 0xf1, 0x60, 0x15, 0x84, 0xf6, 0x67,
+
+	0x38, 0xa9, 0xdb, 0x4a, 0x3f, 0xae, 0xdc, 0x4d,
+	0x36, 0xa7, 0xd5, 0x44, 0x31, 0xa0, 0xd2, 0x43,
+	0x24, 0xb5, 0xc7, 0x56, 0x23, 0xb2, 0xc0, 0x51,
+	0x2a, 0xbb, 0xc9, 0x58, 0x2d, 0xbc, 0xce, 0x5f,
+
+	0x70, 0xe1, 0x93, 0x02, 0x77, 0xe6, 0x94, 0x05,
+	0x7e, 0xef, 0x9d, 0x0c, 0x79, 0xe8, 0x9a, 0x0b,
+	0x6c, 0xfd, 0x8f, 0x1e, 0x6b, 0xfa, 0x88, 0x19,
+	0x62, 0xf3, 0x81, 0x10, 0x65, 0xf4, 0x86, 0x17,
+
+	0x48, 0xd9, 0xab, 0x3a, 0x4f, 0xde, 0xac, 0x3d,
+	0x46, 0xd7, 0xa5, 0x34, 0x41, 0xd0, 0xa2, 0x33,
+	0x54, 0xc5, 0xb7, 0x26, 0x53, 0xc2, 0xb0, 0x21,
+	0x5a, 0xcb, 0xb9, 0x28, 0x5d, 0xcc, 0xbe, 0x2f,
+
+	0xe0, 0x71, 0x03, 0x92, 0xe7, 0x76, 0x04, 0x95,
+	0xee, 0x7f, 0x0d, 0x9c, 0xe9, 0x78, 0x0a, 0x9b,
+	0xfc, 0x6d, 0x1f, 0x8e, 0xfb, 0x6a, 0x18, 0x89,
+	0xf2, 0x63, 0x11, 0x80, 0xf5, 0x64, 0x16, 0x87,
+
+	0xd8, 0x49, 0x3b, 0xaa, 0xdf, 0x4e, 0x3c, 0xad,
+	0xd6, 0x47, 0x35, 0xa4, 0xd1, 0x40, 0x32, 0xa3,
+	0xc4, 0x55, 0x27, 0xb6, 0xc3, 0x52, 0x20, 0xb1,
+	0xca, 0x5b, 0x29, 0xb8, 0xcd, 0x5c, 0x2e, 0xbf,
+
+	0x90, 0x01, 0x73, 0xe2, 0x97, 0x06, 0x74, 0xe5,
+	0x9e, 0x0f, 0x7d, 0xec, 0x99, 0x08, 0x7a, 0xeb,
+	0x8c, 0x1d, 0x6f, 0xfe, 0x8b, 0x1a, 0x68, 0xf9,
+	0x82, 0x13, 0x61, 0xf0, 0x85, 0x14, 0x66, 0xf7,
+
+	0xa8, 0x39, 0x4b, 0xda, 0xaf, 0x3e, 0x4c, 0xdd,
+	0xa6, 0x37, 0x45, 0xd4, 0xa1, 0x30, 0x42, 0xd3,
+	0xb4, 0x25, 0x57, 0xc6, 0xb3, 0x22, 0x50, 0xc1,
+	0xba, 0x2b, 0x59, 0xc8, 0xbd, 0x2c, 0x5e, 0xcf
+};
+
+#define FCS(f, d)	crctable[(f) ^ (d)]
+
+/*
+ * rfcomm_init()
+ *
+ * initialize the "credit pool".
+ */
+void
+rfcomm_init(void)
+{
+	pool_init(&rfcomm_credit_pool, 0, 0, 0, 0, "rfcomm_credit", NULL);
+}
+
+/*
+ * rfcomm_session_alloc(list, sockaddr)
+ *
+ * allocate a new session and fill in the blanks, then
+ * attach session to front of specified list (active or listen)
+ */
+struct rfcomm_session *
+rfcomm_session_alloc(struct rfcomm_session_list *list,
+			struct sockaddr_bt *laddr)
+{
+	struct rfcomm_session *rs;
+	int err;
+
+	rs = malloc(sizeof(*rs), M_BLUETOOTH, M_NOWAIT);
+	if (rs == NULL)
+		return NULL;
+	bzero(rs, sizeof *rs);
+
+	rs->rs_state = RFCOMM_SESSION_CLOSED;
+
+	timeout_set(&rs->rs_timeout, rfcomm_session_timeout, rs);
+
+	SIMPLEQ_INIT(&rs->rs_credits);
+	LIST_INIT(&rs->rs_dlcs);
+
+	err = l2cap_attach(&rs->rs_l2cap, &rfcomm_session_proto, rs);
+	if (err) {
+		free(rs, M_BLUETOOTH);
+		return NULL;
+	}
+
+	(void)l2cap_getopt(rs->rs_l2cap, SO_L2CAP_OMTU, &rs->rs_mtu);
+
+	if (laddr->bt_psm == L2CAP_PSM_ANY)
+		laddr->bt_psm = L2CAP_PSM_RFCOMM;
+
+	(void)l2cap_bind(rs->rs_l2cap, laddr);
+
+	LIST_INSERT_HEAD(list, rs, rs_next);
+
+	return rs;
+}
+
+/*
+ * rfcomm_session_free(rfcomm_session)
+ *
+ * release a session, including any cleanup
+ */
+void
+rfcomm_session_free(struct rfcomm_session *rs)
+{
+	struct rfcomm_credit *credit;
+
+	KASSERT(rs != NULL);
+	KASSERT(LIST_EMPTY(&rs->rs_dlcs));
+
+	rs->rs_state = RFCOMM_SESSION_CLOSED;
+
+	/*
+	 * If the callout is already invoked we have no way to stop it,
+	 * but it will call us back right away (there are no DLC's) so
+	 * not to worry.
+	 */
+	timeout_del(&rs->rs_timeout);
+	if (timeout_triggered(&rs->rs_timeout))
+		return;
+
+	/*
+	 * Take care that rfcomm_session_disconnected() doesnt call
+	 * us back either as it will do if the l2cap_channel has not
+	 * been closed when we detach it..
+	 */
+	if (rs->rs_flags & RFCOMM_SESSION_FREE)
+		return;
+
+	rs->rs_flags |= RFCOMM_SESSION_FREE;
+
+	/* throw away any remaining credit notes */
+	while ((credit = SIMPLEQ_FIRST(&rs->rs_credits)) != NULL) {
+		SIMPLEQ_REMOVE_HEAD(&rs->rs_credits, rc_next);
+		pool_put(&rfcomm_credit_pool, credit);
+	}
+
+	KASSERT(SIMPLEQ_EMPTY(&rs->rs_credits));
+
+	/* Goodbye! */
+	LIST_REMOVE(rs, rs_next);
+	l2cap_detach(&rs->rs_l2cap);
+	free(rs, M_BLUETOOTH);
+}
+
+/*
+ * rfcomm_session_lookup(sockaddr, sockaddr)
+ *
+ * Find active rfcomm session matching src and dest addresses
+ * when src is BDADDR_ANY match any local address
+ */
+struct rfcomm_session *
+rfcomm_session_lookup(struct sockaddr_bt *src, struct sockaddr_bt *dest)
+{
+	struct rfcomm_session *rs;
+	struct sockaddr_bt addr;
+
+	LIST_FOREACH(rs, &rfcomm_session_active, rs_next) {
+		if (rs->rs_state == RFCOMM_SESSION_CLOSED)
+			continue;
+
+		l2cap_sockaddr(rs->rs_l2cap, &addr);
+
+		if (bdaddr_same(&src->bt_bdaddr, &addr.bt_bdaddr) == 0)
+			if (bdaddr_any(&src->bt_bdaddr) == 0)
+				continue;
+
+		l2cap_peeraddr(rs->rs_l2cap, &addr);
+
+		if (addr.bt_psm != dest->bt_psm)
+			continue;
+
+		if (bdaddr_same(&dest->bt_bdaddr, &addr.bt_bdaddr))
+			break;
+	}
+
+	return rs;
+}
+
+/*
+ * rfcomm_session_timeout(rfcomm_session)
+ *
+ * Session timeouts are scheduled when a session is left or
+ * created with no DLCs, and when SABM(0) or DISC(0) are
+ * sent.
+ *
+ * So, if it is in an open state with DLC's attached then
+ * we leave it alone, otherwise the session is lost.
+ */
+static void
+rfcomm_session_timeout(void *arg)
+{
+	struct rfcomm_session *rs = arg;
+	struct rfcomm_dlc *dlc;
+	int s;
+
+	KASSERT(rs != NULL);
+
+	s = splsoftnet();
+
+	if (rs->rs_state != RFCOMM_SESSION_OPEN) {
+		DPRINTF("timeout\n");
+		rs->rs_state = RFCOMM_SESSION_CLOSED;
+
+		while (!LIST_EMPTY(&rs->rs_dlcs)) {
+			dlc = LIST_FIRST(&rs->rs_dlcs);
+
+			rfcomm_dlc_close(dlc, ETIMEDOUT);
+		}
+	}
+
+	if (LIST_EMPTY(&rs->rs_dlcs)) {
+		DPRINTF("expiring\n");
+		rfcomm_session_free(rs);
+	}
+	splx(s);
+}
+
+/***********************************************************************
+ *
+ *	RFCOMM Session L2CAP protocol callbacks
+ *
+ */
+
+static void
+rfcomm_session_connecting(void *arg)
+{
+	/* struct rfcomm_session *rs = arg; */
+
+	DPRINTF("Connecting\n");
+}
+
+static void
+rfcomm_session_connected(void *arg)
+{
+	struct rfcomm_session *rs = arg;
+
+	DPRINTF("Connected\n");
+
+	/*
+	 * L2CAP is open.
+	 *
+	 * If we are initiator, we can send our SABM(0)
+	 * a timeout should be active?
+	 *
+	 * We must take note of the L2CAP MTU because currently
+	 * the L2CAP implementation can only do Basic Mode.
+	 */
+	l2cap_getopt(rs->rs_l2cap, SO_L2CAP_OMTU, &rs->rs_mtu);
+
+	rs->rs_mtu -= 6; /* (RFCOMM overhead could be this big) */
+	if (rs->rs_mtu < RFCOMM_MTU_MIN) {
+		rfcomm_session_disconnected(rs, EINVAL);
+		return;
+	}
+
+	if (IS_INITIATOR(rs)) {
+		int err;
+
+		err = rfcomm_session_send_frame(rs, RFCOMM_FRAME_SABM, 0);
+		if (err)
+			rfcomm_session_disconnected(rs, err);
+
+		timeout_add(&rs->rs_timeout, rfcomm_ack_timeout * hz);
+	}
+}
+
+static void
+rfcomm_session_disconnected(void *arg, int err)
+{
+	struct rfcomm_session *rs = arg;
+	struct rfcomm_dlc *dlc;
+
+	DPRINTF("Disconnected\n");
+
+	rs->rs_state = RFCOMM_SESSION_CLOSED;
+
+	while (!LIST_EMPTY(&rs->rs_dlcs)) {
+		dlc = LIST_FIRST(&rs->rs_dlcs);
+
+		rfcomm_dlc_close(dlc, err);
+	}
+
+	rfcomm_session_free(rs);
+}
+
+static void *
+rfcomm_session_newconn(void *arg, struct sockaddr_bt *laddr,
+				struct sockaddr_bt *raddr)
+{
+	struct rfcomm_session *new, *rs = arg;
+
+	DPRINTF("New Connection\n");
+
+	/*
+	 * Incoming session connect request. We should return a new
+	 * session pointer if this is acceptable. The L2CAP layer
+	 * passes local and remote addresses, which we must check as
+	 * only one RFCOMM session is allowed between any two devices
+	 */
+	new = rfcomm_session_lookup(laddr, raddr);
+	if (new != NULL)
+		return NULL;
+
+	new = rfcomm_session_alloc(&rfcomm_session_active, laddr);
+	if (new == NULL)
+		return NULL;
+
+	new->rs_mtu = rs->rs_mtu;
+	new->rs_state = RFCOMM_SESSION_WAIT_CONNECT;
+
+	/*
+	 * schedule an expiry so that if nothing comes of it we
+	 * can punt.
+	 */
+	timeout_add(&new->rs_timeout, rfcomm_mcc_timeout * hz);
+
+	return new->rs_l2cap;
+}
+
+static void
+rfcomm_session_complete(void *arg, int count)
+{
+	struct rfcomm_session *rs = arg;
+	struct rfcomm_credit *credit;
+	struct rfcomm_dlc *dlc;
+
+	/*
+	 * count L2CAP packets are 'complete', meaning that they are cleared
+	 * our buffers (for best effort) or arrived safe (for guaranteed) so
+	 * we can take it off our list and pass the message on, so that
+	 * eventually the data can be removed from the sockbuf
+	 */
+	while (count-- > 0) {
+		credit = SIMPLEQ_FIRST(&rs->rs_credits);
+#ifdef DIAGNOSTIC
+		if (credit == NULL) {
+			printf("%s: too many packets completed!\n", __func__);
+			break;
+		}
+#endif
+		dlc = credit->rc_dlc;
+		if (dlc != NULL) {
+			dlc->rd_pending--;
+			(*dlc->rd_proto->complete)
+					(dlc->rd_upper, credit->rc_len);
+
+			/*
+			 * if not using credit flow control, we may push
+			 * more data now
+			 */
+			if ((rs->rs_flags & RFCOMM_SESSION_CFC) == 0
+			    && dlc->rd_state == RFCOMM_DLC_OPEN) {
+				rfcomm_dlc_start(dlc);
+			}
+
+			/*
+			 * When shutdown is indicated, we are just waiting to
+			 * clear outgoing data.
+			 */
+			if ((dlc->rd_flags & RFCOMM_DLC_SHUTDOWN)
+			    && dlc->rd_txbuf == NULL && dlc->rd_pending == 0) {
+				dlc->rd_state = RFCOMM_DLC_WAIT_DISCONNECT;
+				rfcomm_session_send_frame(rs, RFCOMM_FRAME_DISC,
+							    dlc->rd_dlci);
+				timeout_add(&dlc->rd_timeout,
+				    rfcomm_ack_timeout * hz);
+			}
+		}
+
+		SIMPLEQ_REMOVE_HEAD(&rs->rs_credits, rc_next);
+		pool_put(&rfcomm_credit_pool, credit);
+	}
+
+	/*
+	 * If session is closed, we are just waiting to clear the queue
+	 */
+	if (rs->rs_state == RFCOMM_SESSION_CLOSED) {
+		if (SIMPLEQ_EMPTY(&rs->rs_credits))
+			l2cap_disconnect(rs->rs_l2cap, 0);
+	}
+}
+
+/*
+ * Link Mode changed
+ *
+ * This is called when a mode change is complete. Proceed with connections
+ * where appropriate, or pass the new mode to any active DLCs.
+ */
+static void
+rfcomm_session_linkmode(void *arg, int new)
+{
+	struct rfcomm_session *rs = arg;
+	struct rfcomm_dlc *dlc, *next;
+	int err, mode = 0;
+
+	DPRINTF("auth %s, encrypt %s, secure %s\n",
+		(new & L2CAP_LM_AUTH ? "on" : "off"),
+		(new & L2CAP_LM_ENCRYPT ? "on" : "off"),
+		(new & L2CAP_LM_SECURE ? "on" : "off"));
+
+	if (new & L2CAP_LM_AUTH)
+		mode |= RFCOMM_LM_AUTH;
+
+	if (new & L2CAP_LM_ENCRYPT)
+		mode |= RFCOMM_LM_ENCRYPT;
+
+	if (new & L2CAP_LM_SECURE)
+		mode |= RFCOMM_LM_SECURE;
+
+	next = LIST_FIRST(&rs->rs_dlcs);
+	while ((dlc = next) != NULL) {
+		next = LIST_NEXT(dlc, rd_next);
+
+		switch (dlc->rd_state) {
+		case RFCOMM_DLC_WAIT_SEND_SABM:	/* we are connecting */
+			if ((mode & dlc->rd_mode) != dlc->rd_mode) {
+				rfcomm_dlc_close(dlc, ECONNABORTED);
+			} else {
+				err = rfcomm_session_send_frame(rs,
+					    RFCOMM_FRAME_SABM, dlc->rd_dlci);
+				if (err) {
+					rfcomm_dlc_close(dlc, err);
+				} else {
+					dlc->rd_state = RFCOMM_DLC_WAIT_RECV_UA;
+					timeout_add(&dlc->rd_timeout,
+					    rfcomm_ack_timeout * hz);
+					break;
+				}
+			}
+
+			/*
+			 * If we aborted the connection and there are no more DLCs
+			 * on the session, it is our responsibility to disconnect.
+			 */
+			if (!LIST_EMPTY(&rs->rs_dlcs))
+				break;
+
+			rs->rs_state = RFCOMM_SESSION_WAIT_DISCONNECT;
+			rfcomm_session_send_frame(rs, RFCOMM_FRAME_DISC, 0);
+			timeout_add(&rs->rs_timeout, rfcomm_ack_timeout * hz);
+			break;
+
+		case RFCOMM_DLC_WAIT_SEND_UA: /* they are connecting */
+			if ((mode & dlc->rd_mode) != dlc->rd_mode) {
+				rfcomm_session_send_frame(rs,
+					    RFCOMM_FRAME_DM, dlc->rd_dlci);
+				rfcomm_dlc_close(dlc, ECONNABORTED);
+				break;
+			}
+
+			err = rfcomm_session_send_frame(rs,
+					    RFCOMM_FRAME_UA, dlc->rd_dlci);
+			if (err) {
+				rfcomm_session_send_frame(rs,
+						RFCOMM_FRAME_DM, dlc->rd_dlci);
+				rfcomm_dlc_close(dlc, err);
+				break;
+			}
+
+			err = rfcomm_dlc_open(dlc);
+			if (err) {
+				rfcomm_session_send_frame(rs,
+						RFCOMM_FRAME_DM, dlc->rd_dlci);
+				rfcomm_dlc_close(dlc, err);
+				break;
+			}
+
+			break;
+
+		case RFCOMM_DLC_WAIT_RECV_UA:
+		case RFCOMM_DLC_OPEN: /* already established */
+			(*dlc->rd_proto->linkmode)(dlc->rd_upper, mode);
+			break;
+
+		default:
+			break;
+		}
+	}
+}
+
+/*
+ * Receive data from L2CAP layer for session. There is always exactly one
+ * RFCOMM frame contained in each L2CAP frame.
+ */
+static void
+rfcomm_session_input(void *arg, struct mbuf *m)
+{
+	struct rfcomm_session *rs = arg;
+	int dlci, len, type, pf;
+	uint8_t fcs, b;
+
+	KASSERT(m != NULL);
+	KASSERT(rs != NULL);
+
+	/*
+	 * UIH frames: FCS is only calculated on address and control fields
+	 * For other frames: FCS is calculated on address, control and length
+	 * Length may extend to two octets
+	 */
+	fcs = 0xff;
+
+	if (m->m_pkthdr.len < 4) {
+		DPRINTF("short frame (%d), discarded\n", m->m_pkthdr.len);
+		goto done;
+	}
+
+	/* address - one octet */
+	m_copydata(m, 0, 1, &b);
+	m_adj(m, 1);
+	fcs = FCS(fcs, b);
+	dlci = RFCOMM_DLCI(b);
+
+	/* control - one octet */
+	m_copydata(m, 0, 1, &b);
+	m_adj(m, 1);
+	fcs = FCS(fcs, b);
+	type = RFCOMM_TYPE(b);
+	pf = RFCOMM_PF(b);
+
+	/* length - may be two octets */
+	m_copydata(m, 0, 1, &b);
+	m_adj(m, 1);
+	if (type != RFCOMM_FRAME_UIH)
+		fcs = FCS(fcs, b);
+	len = (b >> 1) & 0x7f;
+
+	if (RFCOMM_EA(b) == 0) {
+		if (m->m_pkthdr.len < 2) {
+			DPRINTF("short frame (%d, EA = 0), discarded\n",
+				m->m_pkthdr.len);
+			goto done;
+		}
+
+		m_copydata(m, 0, 1, &b);
+		m_adj(m, 1);
+		if (type != RFCOMM_FRAME_UIH)
+			fcs = FCS(fcs, b);
+
+		len |= (b << 7);
+	}
+
+	/* FCS byte is last octet in frame */
+	m_copydata(m, m->m_pkthdr.len - 1, 1, &b);
+	m_adj(m, -1);
+	fcs = FCS(fcs, b);
+
+	if (fcs != 0xcf) {
+		DPRINTF("Bad FCS value (%#2.2x), frame discarded\n", fcs);
+		goto done;
+	}
+
+	DPRINTFN(10, "dlci %d, type %2.2x, len = %d\n", dlci, type, len);
+
+	switch (type) {
+	case RFCOMM_FRAME_SABM:
+		if (pf)
+			rfcomm_session_recv_sabm(rs, dlci);
+		break;
+
+	case RFCOMM_FRAME_DISC:
+		if (pf)
+			rfcomm_session_recv_disc(rs, dlci);
+		break;
+
+	case RFCOMM_FRAME_UA:
+		if (pf)
+			rfcomm_session_recv_ua(rs, dlci);
+		break;
+
+	case RFCOMM_FRAME_DM:
+		rfcomm_session_recv_dm(rs, dlci);
+		break;
+
+	case RFCOMM_FRAME_UIH:
+		rfcomm_session_recv_uih(rs, dlci, pf, m, len);
+		return;	/* (no release) */
+
+	default:
+		UNKNOWN(type);
+		break;
+	}
+
+done:
+	m_freem(m);
+}
+
+/***********************************************************************
+ *
+ *	RFCOMM Session receive processing
+ */
+
+/*
+ * rfcomm_session_recv_sabm(rfcomm_session, dlci)
+ *
+ * Set Asyncrhonous Balanced Mode - open the channel.
+ */
+static void
+rfcomm_session_recv_sabm(struct rfcomm_session *rs, int dlci)
+{
+	struct rfcomm_dlc *dlc;
+	int err;
+
+	DPRINTFN(5, "SABM(%d)\n", dlci);
+
+	if (dlci == 0) {	/* Open Session */
+		rs->rs_state = RFCOMM_SESSION_OPEN;
+		rfcomm_session_send_frame(rs, RFCOMM_FRAME_UA, 0);
+		LIST_FOREACH(dlc, &rs->rs_dlcs, rd_next) {
+			if (dlc->rd_state == RFCOMM_DLC_WAIT_SESSION)
+				rfcomm_dlc_connect(dlc);
+		}
+		return;
+	}
+
+	if (rs->rs_state != RFCOMM_SESSION_OPEN) {
+		DPRINTF("session was not even open!\n");
+		return;
+	}
+
+	/* validate direction bit */
+	if ((IS_INITIATOR(rs) && !RFCOMM_DIRECTION(dlci))
+	    || (!IS_INITIATOR(rs) && RFCOMM_DIRECTION(dlci))) {
+		DPRINTF("Invalid direction bit on DLCI\n");
+		return;
+	}
+
+	/*
+	 * look for our DLC - this may exist if we received PN
+	 * already, or we may have to fabricate a new one.
+	 */
+	dlc = rfcomm_dlc_lookup(rs, dlci);
+	if (dlc == NULL) {
+		dlc = rfcomm_dlc_newconn(rs, dlci);
+		if (dlc == NULL)
+			return;	/* (DM is sent) */
+	}
+
+	/*
+	 * ..but if this DLC is not waiting to connect, they did
+	 * something wrong, ignore it.
+	 */
+	if (dlc->rd_state != RFCOMM_DLC_WAIT_CONNECT)
+		return;
+
+	/* set link mode */
+	err = rfcomm_dlc_setmode(dlc);
+	if (err == EINPROGRESS) {
+		dlc->rd_state = RFCOMM_DLC_WAIT_SEND_UA;
+		(*dlc->rd_proto->connecting)(dlc->rd_upper);
+		return;
+	}
+	if (err)
+		goto close;
+
+	err = rfcomm_session_send_frame(rs, RFCOMM_FRAME_UA, dlci);
+	if (err)
+		goto close;
+
+	/* and mark it open */
+	err = rfcomm_dlc_open(dlc);
+	if (err)
+		goto close;
+
+	return;
+
+close:
+	rfcomm_dlc_close(dlc, err);
+}
+
+/*
+ * Receive Disconnect Command
+ */
+static void
+rfcomm_session_recv_disc(struct rfcomm_session *rs, int dlci)
+{
+	struct rfcomm_dlc *dlc;
+
+	DPRINTFN(5, "DISC(%d)\n", dlci);
+
+	if (dlci == 0) {
+		/*
+		 * Disconnect Session
+		 *
+		 * We set the session state to CLOSED so that when
+		 * the UA frame is clear the session will be closed
+		 * automatically. We wont bother to close any DLC's
+		 * just yet as there should be none. In the unlikely
+		 * event that something is left, it will get flushed
+		 * out as the session goes down.
+		 */
+		rfcomm_session_send_frame(rs, RFCOMM_FRAME_UA, 0);
+		rs->rs_state = RFCOMM_SESSION_CLOSED;
+		return;
+	}
+
+	dlc = rfcomm_dlc_lookup(rs, dlci);
+	if (dlc == NULL) {
+		rfcomm_session_send_frame(rs, RFCOMM_FRAME_DM, dlci);
+		return;
+	}
+
+	rfcomm_dlc_close(dlc, ECONNRESET);
+	rfcomm_session_send_frame(rs, RFCOMM_FRAME_UA, dlci);
+}
+
+/*
+ * Receive Unnumbered Acknowledgement Response
+ *
+ * This should be a response to a DISC or SABM frame that we
+ * have previously sent. If unexpected, ignore it.
+ */
+static void
+rfcomm_session_recv_ua(struct rfcomm_session *rs, int dlci)
+{
+	struct rfcomm_dlc *dlc;
+
+	DPRINTFN(5, "UA(%d)\n", dlci);
+
+	if (dlci == 0) {
+		switch (rs->rs_state) {
+		case RFCOMM_SESSION_WAIT_CONNECT:	/* We sent SABM */
+			timeout_del(&rs->rs_timeout);
+			rs->rs_state = RFCOMM_SESSION_OPEN;
+			LIST_FOREACH(dlc, &rs->rs_dlcs, rd_next) {
+				if (dlc->rd_state == RFCOMM_DLC_WAIT_SESSION)
+					rfcomm_dlc_connect(dlc);
+			}
+			break;
+
+		case RFCOMM_SESSION_WAIT_DISCONNECT:	/* We sent DISC */
+			timeout_del(&rs->rs_timeout);
+			rs->rs_state = RFCOMM_SESSION_CLOSED;
+			l2cap_disconnect(rs->rs_l2cap, 0);
+			break;
+
+		default:
+			DPRINTF("Received spurious UA(0)!\n");
+			break;
+		}
+
+		return;
+	}
+
+	/*
+	 * If we have no DLC on this dlci, we may have aborted
+	 * without shutting down properly, so check if the session
+	 * needs disconnecting.
+	 */
+	dlc = rfcomm_dlc_lookup(rs, dlci);
+	if (dlc == NULL)
+		goto check;
+
+	switch (dlc->rd_state) {
+	case RFCOMM_DLC_WAIT_RECV_UA:		/* We sent SABM */
+		rfcomm_dlc_open(dlc);
+		return;
+
+	case RFCOMM_DLC_WAIT_DISCONNECT:	/* We sent DISC */
+		rfcomm_dlc_close(dlc, 0);
+		break;
+
+	default:
+		DPRINTF("Received spurious UA(%d)!\n", dlci);
+		return;
+	}
+
+check:	/* last one out turns out the light */
+	if (LIST_EMPTY(&rs->rs_dlcs)) {
+		rs->rs_state = RFCOMM_SESSION_WAIT_DISCONNECT;
+		rfcomm_session_send_frame(rs, RFCOMM_FRAME_DISC, 0);
+		timeout_add(&rs->rs_timeout, rfcomm_ack_timeout * hz);
+	}
+}
+
+/*
+ * Receive Disconnected Mode Response
+ *
+ * If this does not apply to a known DLC then we may ignore it.
+ */
+static void
+rfcomm_session_recv_dm(struct rfcomm_session *rs, int dlci)
+{
+	struct rfcomm_dlc *dlc;
+
+	DPRINTFN(5, "DM(%d)\n", dlci);
+
+	dlc = rfcomm_dlc_lookup(rs, dlci);
+	if (dlc == NULL)
+		return;
+
+	if (dlc->rd_state == RFCOMM_DLC_WAIT_CONNECT)
+		rfcomm_dlc_close(dlc, ECONNREFUSED);
+	else
+		rfcomm_dlc_close(dlc, ECONNRESET);
+}
+
+/*
+ * Receive Unnumbered Information with Header check (MCC or data packet)
+ */
+static void
+rfcomm_session_recv_uih(struct rfcomm_session *rs, int dlci,
+			int pf, struct mbuf *m, int len)
+{
+	struct rfcomm_dlc *dlc;
+	uint8_t credits = 0;
+
+	DPRINTFN(10, "UIH(%d)\n", dlci);
+
+	if (dlci == 0) {
+		rfcomm_session_recv_mcc(rs, m);
+		return;
+	}
+
+	if (m->m_pkthdr.len != len + pf) {
+		DPRINTF("Bad Frame Length (%d), frame discarded\n",
+			    m->m_pkthdr.len);
+
+		goto discard;
+	}
+
+	dlc = rfcomm_dlc_lookup(rs, dlci);
+	if (dlc == NULL) {
+		DPRINTF("UIH received for non existent DLC, discarded\n");
+		rfcomm_session_send_frame(rs, RFCOMM_FRAME_DM, dlci);
+		goto discard;
+	}
+
+	if (dlc->rd_state != RFCOMM_DLC_OPEN) {
+		DPRINTF("non-open DLC (state = %d), discarded\n",
+				dlc->rd_state);
+		goto discard;
+	}
+
+	/* if PF is set, credits were included */
+	if (rs->rs_flags & RFCOMM_SESSION_CFC) {
+		if (pf != 0) {
+			if (m->m_pkthdr.len < sizeof(credits)) {
+				DPRINTF("Bad PF value, UIH discarded\n");
+				goto discard;
+			}
+
+			m_copydata(m, 0, sizeof(credits), &credits);
+			m_adj(m, sizeof(credits));
+
+			dlc->rd_txcred += credits;
+
+			if (credits > 0 && dlc->rd_txbuf != NULL)
+				rfcomm_dlc_start(dlc);
+		}
+
+		if (len == 0)
+			goto discard;
+
+		if (dlc->rd_rxcred == 0) {
+			DPRINTF("Credit limit reached, UIH discarded\n");
+			goto discard;
+		}
+
+		if (len > dlc->rd_rxsize) {
+			DPRINTF("UIH frame exceeds rxsize, discarded\n");
+			goto discard;
+		}
+
+		dlc->rd_rxcred--;
+		dlc->rd_rxsize -= len;
+	}
+
+	(*dlc->rd_proto->input)(dlc->rd_upper, m);
+	return;
+
+discard:
+	m_freem(m);
+}
+
+/*
+ * Receive Multiplexer Control Command
+ */
+static void
+rfcomm_session_recv_mcc(struct rfcomm_session *rs, struct mbuf *m)
+{
+	int type, cr, len;
+	uint8_t b;
+
+	/*
+	 * Extract MCC header.
+	 *
+	 * Fields are variable length using extension bit = 1 to signify the
+	 * last octet in the sequence.
+	 *
+	 * Only single octet types are defined in TS 07.10/RFCOMM spec
+	 *
+	 * Length can realistically only use 15 bits (max RFCOMM MTU)
+	 */
+	if (m->m_pkthdr.len < sizeof(b)) {
+		DPRINTF("Short MCC header, discarded\n");
+		goto release;
+	}
+
+	m_copydata(m, 0, sizeof(b), &b);
+	m_adj(m, sizeof(b));
+
+	if (RFCOMM_EA(b) == 0) {	/* verify no extensions */
+		DPRINTF("MCC type EA = 0, discarded\n");
+		goto release;
+	}
+
+	type = RFCOMM_MCC_TYPE(b);
+	cr = RFCOMM_CR(b);
+
+	len = 0;
+	do {
+		if (m->m_pkthdr.len < sizeof(b)) {
+			DPRINTF("Short MCC header, discarded\n");
+			goto release;
+		}
+
+		m_copydata(m, 0, sizeof(b), &b);
+		m_adj(m, sizeof(b));
+
+		len = (len << 7) | (b >> 1);
+		len = min(len, RFCOMM_MTU_MAX);
+	} while (RFCOMM_EA(b) == 0);
+
+	if (len != m->m_pkthdr.len) {
+		DPRINTF("Incorrect MCC length, discarded\n");
+		goto release;
+	}
+
+	DPRINTFN(2, "MCC %s type %2.2x (%d bytes)\n",
+		(cr ? "command" : "response"), type, len);
+
+	/*
+	 * pass to command handler
+	 */
+	switch(type) {
+	case RFCOMM_MCC_TEST:	/* Test */
+		rfcomm_session_recv_mcc_test(rs, cr, m);
+		break;
+
+	case RFCOMM_MCC_FCON:	/* Flow Control On */
+		rfcomm_session_recv_mcc_fcon(rs, cr);
+		break;
+
+	case RFCOMM_MCC_FCOFF:	/* Flow Control Off */
+		rfcomm_session_recv_mcc_fcoff(rs, cr);
+		break;
+
+	case RFCOMM_MCC_MSC:	/* Modem Status Command */
+		rfcomm_session_recv_mcc_msc(rs, cr, m);
+		break;
+
+	case RFCOMM_MCC_RPN:	/* Remote Port Negotiation */
+		rfcomm_session_recv_mcc_rpn(rs, cr, m);
+		break;
+
+	case RFCOMM_MCC_RLS:	/* Remote Line Status */
+		rfcomm_session_recv_mcc_rls(rs, cr, m);
+		break;
+
+	case RFCOMM_MCC_PN:	/* Parameter Negotiation */
+		rfcomm_session_recv_mcc_pn(rs, cr, m);
+		break;
+
+	case RFCOMM_MCC_NSC:	/* Non Supported Command */
+		rfcomm_session_recv_mcc_nsc(rs, cr, m);
+		break;
+
+	default:
+		b = RFCOMM_MKMCC_TYPE(cr, type);
+		rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_NSC, &b, sizeof(b));
+	}
+
+release:
+	m_freem(m);
+}
+
+/*
+ * process TEST command/response
+ */
+static void
+rfcomm_session_recv_mcc_test(struct rfcomm_session *rs, int cr, struct mbuf *m)
+{
+	void *data;
+	int len;
+
+	if (cr == 0)	/* ignore ack */
+		return;
+
+	/*
+	 * we must send all the data they included back as is
+	 */
+
+	len = m->m_pkthdr.len;
+	if (len > RFCOMM_MTU_MAX)
+		return;
+
+	data = malloc(len, M_BLUETOOTH, M_NOWAIT);
+	if (data == NULL)
+		return;
+
+	m_copydata(m, 0, len, data);
+	rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_TEST, data, len);
+	free(data, M_BLUETOOTH);
+}
+
+/*
+ * process Flow Control ON command/response
+ */
+static void
+rfcomm_session_recv_mcc_fcon(struct rfcomm_session *rs, int cr)
+{
+
+	if (cr == 0)	/* ignore ack */
+		return;
+
+	rs->rs_flags |= RFCOMM_SESSION_RFC;
+	rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_FCON, NULL, 0);
+}
+
+/*
+ * process Flow Control OFF command/response
+ */
+static void
+rfcomm_session_recv_mcc_fcoff(struct rfcomm_session *rs, int cr)
+{
+
+	if (cr == 0)	/* ignore ack */
+		return;
+
+	rs->rs_flags &= ~RFCOMM_SESSION_RFC;
+	rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_FCOFF, NULL, 0);
+}
+
+/*
+ * process Modem Status Command command/response
+ */
+static void
+rfcomm_session_recv_mcc_msc(struct rfcomm_session *rs, int cr, struct mbuf *m)
+{
+	struct rfcomm_mcc_msc msc;	/* (3 octets) */
+	struct rfcomm_dlc *dlc;
+	int len = 0;
+
+	/* [ADDRESS] */
+	if (m->m_pkthdr.len < sizeof(msc.address))
+		return;
+
+	m_copydata(m, 0, sizeof(msc.address), &msc.address);
+	m_adj(m, sizeof(msc.address));
+	len += sizeof(msc.address);
+
+	dlc = rfcomm_dlc_lookup(rs, RFCOMM_DLCI(msc.address));
+
+	if (cr == 0) {	/* ignore acks */
+		if (dlc != NULL)
+			timeout_del(&dlc->rd_timeout);
+
+		return;
+	}
+
+	if (dlc == NULL) {
+		rfcomm_session_send_frame(rs, RFCOMM_FRAME_DM,
+						RFCOMM_DLCI(msc.address));
+		return;
+	}
+
+	/* [SIGNALS] */
+	if (m->m_pkthdr.len < sizeof(msc.modem))
+		return;
+
+	m_copydata(m, 0, sizeof(msc.modem), &msc.modem);
+	m_adj(m, sizeof(msc.modem));
+	len += sizeof(msc.modem);
+
+	dlc->rd_rmodem = msc.modem;
+	/* XXX how do we signal this upstream? */
+
+	if (RFCOMM_EA(msc.modem) == 0) {
+		if (m->m_pkthdr.len < sizeof(msc.brk))
+			return;
+
+		m_copydata(m, 0, sizeof(msc.brk), &msc.brk);
+		m_adj(m, sizeof(msc.brk));
+		len += sizeof(msc.brk);
+
+		/* XXX how do we signal this upstream? */
+	}
+
+	rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_MSC, &msc, len);
+}
+
+/*
+ * process Remote Port Negotiation command/response
+ */
+static void
+rfcomm_session_recv_mcc_rpn(struct rfcomm_session *rs, int cr, struct mbuf *m)
+{
+	struct rfcomm_mcc_rpn rpn;
+	uint16_t mask;
+
+	if (cr == 0)	/* ignore ack */
+		return;
+
+	/* default values */
+	rpn.bit_rate = RFCOMM_RPN_BR_9600;
+	rpn.line_settings = RFCOMM_RPN_8_N_1;
+	rpn.flow_control = RFCOMM_RPN_FLOW_NONE;
+	rpn.xon_char = RFCOMM_RPN_XON_CHAR;
+	rpn.xoff_char = RFCOMM_RPN_XOFF_CHAR;
+
+	if (m->m_pkthdr.len == sizeof(rpn)) {
+		m_copydata(m, 0, sizeof(rpn), (caddr_t)&rpn);
+		rpn.param_mask = RFCOMM_RPN_PM_ALL;
+	} else if (m->m_pkthdr.len == 1) {
+		m_copydata(m, 0, 1, (caddr_t)&rpn);
+		rpn.param_mask = letoh16(rpn.param_mask);
+	} else {
+		DPRINTF("Bad RPN length (%d)\n", m->m_pkthdr.len);
+		return;
+	}
+
+	mask = 0;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_RATE)
+		mask |= RFCOMM_RPN_PM_RATE;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_DATA
+	    && RFCOMM_RPN_DATA_BITS(rpn.line_settings) == RFCOMM_RPN_DATA_8)
+		mask |= RFCOMM_RPN_PM_DATA;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_STOP
+	    && RFCOMM_RPN_STOP_BITS(rpn.line_settings) == RFCOMM_RPN_STOP_1)
+		mask |= RFCOMM_RPN_PM_STOP;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_PARITY
+	    && RFCOMM_RPN_PARITY(rpn.line_settings) == RFCOMM_RPN_PARITY_NONE)
+		mask |= RFCOMM_RPN_PM_PARITY;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_XON
+	    && rpn.xon_char == RFCOMM_RPN_XON_CHAR)
+		mask |= RFCOMM_RPN_PM_XON;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_XOFF
+	    && rpn.xoff_char == RFCOMM_RPN_XOFF_CHAR)
+		mask |= RFCOMM_RPN_PM_XOFF;
+
+	if (rpn.param_mask & RFCOMM_RPN_PM_FLOW
+	    && rpn.flow_control == RFCOMM_RPN_FLOW_NONE)
+		mask |= RFCOMM_RPN_PM_FLOW;
+
+	rpn.param_mask = htole16(mask);
+
+	rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_RPN, &rpn, sizeof(rpn));
+}
+
+/*
+ * process Remote Line Status command/response
+ */
+static void
+rfcomm_session_recv_mcc_rls(struct rfcomm_session *rs, int cr, struct mbuf *m)
+{
+	struct rfcomm_mcc_rls rls;
+
+	if (cr == 0)	/* ignore ack */
+		return;
+
+	if (m->m_pkthdr.len != sizeof(rls)) {
+		DPRINTF("Bad RLS length %d\n", m->m_pkthdr.len);
+		return;
+	}
+
+	m_copydata(m, 0, sizeof(rls), (caddr_t)&rls);
+
+	/*
+	 * So far as I can tell, we just send back what
+	 * they sent us. This signifies errors that seem
+	 * irrelevent for RFCOMM over L2CAP.
+	 */
+	rls.address |= 0x03;	/* EA = 1, CR = 1 */
+	rls.status &= 0x0f;	/* only 4 bits valid */
+
+	rfcomm_session_send_mcc(rs, 0, RFCOMM_MCC_RLS, &rls, sizeof(rls));
+}
+
+/*
+ * process Parameter Negotiation command/response
+ */
+static void
+rfcomm_session_recv_mcc_pn(struct rfcomm_session *rs, int cr, struct mbuf *m)
+{
+	struct rfcomm_dlc *dlc;
+	struct rfcomm_mcc_pn pn;
+	int err;
+
+	if (m->m_pkthdr.len != sizeof(pn)) {
+		DPRINTF("Bad PN length %d\n", m->m_pkthdr.len);
+		return;
+	}
+
+	m_copydata(m, 0, sizeof(pn), (caddr_t)&pn);
+
+	pn.dlci &= 0x3f;
+	pn.mtu = letoh16(pn.mtu);
+
+	dlc = rfcomm_dlc_lookup(rs, pn.dlci);
+	if (cr) {	/* Command */
+		/*
+		 * If there is no DLC present, this is a new
+		 * connection so attempt to make one
+		 */
+		if (dlc == NULL) {
+			dlc = rfcomm_dlc_newconn(rs, pn.dlci);
+			if (dlc == NULL)
+				return;	/* (DM is sent) */
+		}
+
+		/* accept any valid MTU, and offer it back */
+		pn.mtu = min(pn.mtu, RFCOMM_MTU_MAX);
+		pn.mtu = min(pn.mtu, rs->rs_mtu);
+		pn.mtu = max(pn.mtu, RFCOMM_MTU_MIN);
+		dlc->rd_mtu = pn.mtu;
+		pn.mtu = htole16(pn.mtu);
+
+		/* credits are only set before DLC is open */
+		if (dlc->rd_state == RFCOMM_DLC_WAIT_CONNECT
+		    && (pn.flow_control & 0xf0) == 0xf0) {
+			rs->rs_flags |= RFCOMM_SESSION_CFC;
+			dlc->rd_txcred = pn.credits & 0x07;
+
+			dlc->rd_rxcred = (dlc->rd_rxsize / dlc->rd_mtu);
+			dlc->rd_rxcred = min(dlc->rd_rxcred,
+						RFCOMM_CREDITS_DEFAULT);
+
+			pn.flow_control = 0xe0;
+			pn.credits = dlc->rd_rxcred;
+		} else {
+			pn.flow_control = 0x00;
+			pn.credits = 0x00;
+		}
+
+		/* unused fields must be ignored and set to zero */
+		pn.ack_timer = 0;
+		pn.max_retrans = 0;
+
+		/* send our response */
+		err = rfcomm_session_send_mcc(rs, 0,
+					RFCOMM_MCC_PN, &pn, sizeof(pn));
+		if (err)
+			goto close;
+
+	} else {	/* Response */
+		/* ignore responses with no matching DLC */
+		if (dlc == NULL)
+			return;
+
+		timeout_del(&dlc->rd_timeout);
+
+		if (pn.mtu > RFCOMM_MTU_MAX || pn.mtu > dlc->rd_mtu) {
+			dlc->rd_state = RFCOMM_DLC_WAIT_DISCONNECT;
+			err = rfcomm_session_send_frame(rs, RFCOMM_FRAME_DISC,
+							pn.dlci);
+			if (err)
+				goto close;
+
+			timeout_add(&dlc->rd_timeout,
+			    rfcomm_ack_timeout * hz);
+			return;
+		}
+		dlc->rd_mtu = pn.mtu;
+
+		/* if DLC is not waiting to connect, we are done */
+		if (dlc->rd_state != RFCOMM_DLC_WAIT_CONNECT)
+			return;
+
+		/* set initial credits according to RFCOMM spec */
+		if ((pn.flow_control & 0xf0) == 0xe0) {
+			rs->rs_flags |= RFCOMM_SESSION_CFC;
+			dlc->rd_txcred = (pn.credits & 0x07);
+		}
+
+		timeout_add(&dlc->rd_timeout, rfcomm_ack_timeout * hz);
+
+		/* set link mode */
+		err = rfcomm_dlc_setmode(dlc);
+		if (err == EINPROGRESS) {
+			dlc->rd_state = RFCOMM_DLC_WAIT_SEND_SABM;
+			(*dlc->rd_proto->connecting)(dlc->rd_upper);
+			return;
+		}
+		if (err)
+			goto close;
+
+		/* we can proceed now */
+		err = rfcomm_session_send_frame(rs, RFCOMM_FRAME_SABM, pn.dlci);
+		if (err)
+			goto close;
+
+		dlc->rd_state = RFCOMM_DLC_WAIT_RECV_UA;
+	}
+	return;
+
+close:
+	rfcomm_dlc_close(dlc, err);
+}
+
+/*
+ * process Non Supported Command command/response
+ */
+static void
+rfcomm_session_recv_mcc_nsc(struct rfcomm_session *rs,
+    int cr, struct mbuf *m)
+{
+	struct rfcomm_dlc *dlc, *next;
+
+	/*
+	 * Since we did nothing that is not mandatory,
+	 * we just abort the whole session..
+	 */
+
+	next = LIST_FIRST(&rs->rs_dlcs);
+	while ((dlc = next) != NULL) {
+		next = LIST_NEXT(dlc, rd_next);
+		rfcomm_dlc_close(dlc, ECONNABORTED);
+	}
+
+	rfcomm_session_free(rs);
+}
+
+/***********************************************************************
+ *
+ *	RFCOMM Session outward frame/uih/mcc building
+ */
+
+/*
+ * SABM/DISC/DM/UA frames are all minimal and mostly identical.
+ */
+int
+rfcomm_session_send_frame(struct rfcomm_session *rs, int type, int dlci)
+{
+	struct rfcomm_cmd_hdr *hdr;
+	struct rfcomm_credit *credit;
+	struct mbuf *m;
+	uint8_t fcs, cr;
+
+	credit = pool_get(&rfcomm_credit_pool, PR_NOWAIT);
+	if (credit == NULL)
+		return ENOMEM;
+
+	m = m_gethdr(M_DONTWAIT, MT_DATA);
+	if (m == NULL) {
+		pool_put(&rfcomm_credit_pool, credit);
+		return ENOMEM;
+	}
+
+	/*
+	 * The CR (command/response) bit identifies the frame either as a
+	 * commmand or a response and is used along with the DLCI to form
+	 * the address. Commands contain the non-initiator address, whereas
+	 * responses contain the initiator address, so the CR value is
+	 * also dependent on the session direction.
+	 */
+	if (type == RFCOMM_FRAME_UA || type == RFCOMM_FRAME_DM)
+		cr = IS_INITIATOR(rs) ? 0 : 1;
+	else
+		cr = IS_INITIATOR(rs) ? 1 : 0;
+
+	hdr = mtod(m, struct rfcomm_cmd_hdr *);
+	hdr->address = RFCOMM_MKADDRESS(cr, dlci);
+	hdr->control = RFCOMM_MKCONTROL(type, 1);   /* PF = 1 */
+	hdr->length = (0x00 << 1) | 0x01;	    /* len = 0x00, EA = 1 */
+
+	fcs = 0xff;
+	fcs = FCS(fcs, hdr->address);
+	fcs = FCS(fcs, hdr->control);
+	fcs = FCS(fcs, hdr->length);
+	fcs = 0xff - fcs;	/* ones complement */
+	hdr->fcs = fcs;
+
+	m->m_pkthdr.len = m->m_len = sizeof(struct rfcomm_cmd_hdr);
+
+	/* empty credit note */
+	credit->rc_dlc = NULL;
+	credit->rc_len = m->m_pkthdr.len;
+	SIMPLEQ_INSERT_TAIL(&rs->rs_credits, credit, rc_next);
+
+	DPRINTFN(5, "dlci %d type %2.2x (%d bytes, fcs=%#2.2x)\n",
+		dlci, type, m->m_pkthdr.len, fcs);
+
+	return l2cap_send(rs->rs_l2cap, m);
+}
+
+/*
+ * rfcomm_session_send_uih(rfcomm_session, rfcomm_dlc, credits, mbuf)
+ *
+ * UIH frame is per DLC data or Multiplexer Control Commands
+ * when no DLC is given. Data mbuf is optional (just credits
+ * will be sent in that case)
+ */
+int
+rfcomm_session_send_uih(struct rfcomm_session *rs, struct rfcomm_dlc *dlc,
+			int credits, struct mbuf *m)
+{
+	struct rfcomm_credit *credit;
+	struct mbuf *m0 = NULL;
+	int err, len;
+	uint8_t fcs, *hdr;
+
+	KASSERT(rs != NULL);
+
+	len = (m == NULL) ? 0 : m->m_pkthdr.len;
+	KASSERT(!(credits == 0 && len == 0));
+
+	/*
+	 * Make a credit note for the completion notification
+	 */
+	credit = pool_get(&rfcomm_credit_pool, PR_NOWAIT);
+	if (credit == NULL)
+		goto nomem;
+
+	credit->rc_len = len;
+	credit->rc_dlc = dlc;
+
+	/*
+	 * Wrap UIH frame information around payload.
+	 *
+	 * [ADDRESS] [CONTROL] [LENGTH] [CREDITS] [...] [FCS]
+	 *
+	 * Address is one octet.
+	 * Control is one octet.
+	 * Length is one or two octets.
+	 * Credits may be one octet.
+	 *
+	 * FCS is one octet and calculated on address and
+	 *	control octets only.
+	 *
+	 * If there are credits to be sent, we will set the PF
+	 * flag and include them in the frame.
+	 */
+	m0 = m_gethdr(M_DONTWAIT, MT_DATA);
+	if (m0 == NULL)
+		goto nomem;
+
+	MH_ALIGN(m0, 5);	/* (max 5 header octets) */
+	hdr = mtod(m0, uint8_t *);
+
+	/* CR bit is set according to the initiator of the session */
+	*hdr = RFCOMM_MKADDRESS((IS_INITIATOR(rs) ? 1 : 0),
+				(dlc ? dlc->rd_dlci : 0));
+	fcs = FCS(0xff, *hdr);
+	hdr++;
+
+	/* PF bit is set if credits are being sent */
+	*hdr = RFCOMM_MKCONTROL(RFCOMM_FRAME_UIH, (credits > 0 ? 1 : 0));
+	fcs = FCS(fcs, *hdr);
+	hdr++;
+
+	if (len < (1 << 7)) {
+		*hdr++ = ((len << 1) & 0xfe) | 0x01;	/* 7 bits, EA = 1 */
+	} else {
+		*hdr++ = ((len << 1) & 0xfe);		/* 7 bits, EA = 0 */
+		*hdr++ = ((len >> 7) & 0xff);		/* 8 bits, no EA */
+	}
+
+	if (credits > 0)
+		*hdr++ = (uint8_t)credits;
+
+	m0->m_len = hdr - mtod(m0, uint8_t *);
+
+	/* Append payload */
+	m0->m_next = m;
+	m = NULL;
+
+	m0->m_pkthdr.len = m0->m_len + len;
+
+	/* Append FCS */
+	fcs = 0xff - fcs;	/* ones complement */
+	len = m0->m_pkthdr.len;
+	m_copyback(m0, len, sizeof(fcs), &fcs);
+	if (m0->m_pkthdr.len != len + sizeof(fcs))
+		goto nomem;
+
+	DPRINTFN(10, "dlci %d, pktlen %d (%d data, %d credits), fcs=%#2.2x\n",
+		dlc ? dlc->rd_dlci : 0, m0->m_pkthdr.len, credit->rc_len,
+		credits, fcs);
+
+	/*
+	 * UIH frame ready to go..
+	 */
+	err = l2cap_send(rs->rs_l2cap, m0);
+	if (err)
+		goto fail;
+
+	SIMPLEQ_INSERT_TAIL(&rs->rs_credits, credit, rc_next);
+	return 0;
+
+nomem:
+	err = ENOMEM;
+
+	if (m0 != NULL)
+		m_freem(m0);
+
+	if (m != NULL)
+		m_freem(m);
+
+fail:
+	if (credit != NULL)
+		pool_put(&rfcomm_credit_pool, credit);
+
+	return err;
+}
+
+/*
+ * send Multiplexer Control Command (or Response) on session
+ */
+int
+rfcomm_session_send_mcc(struct rfcomm_session *rs, int cr,
+			uint8_t type, void *data, int len)
+{
+	struct mbuf *m;
+	uint8_t *hdr;
+	int hlen;
+
+	m = m_gethdr(M_DONTWAIT, MT_DATA);
+	if (m == NULL)
+		return ENOMEM;
+
+	hdr = mtod(m, uint8_t *);
+
+	/*
+	 * Technically the type field can extend past one octet, but none
+	 * currently defined will do that.
+	 */
+	*hdr++ = RFCOMM_MKMCC_TYPE(cr, type);
+
+	/*
+	 * In the frame, the max length size is 2 octets (15 bits) whereas
+	 * no max length size is specified for MCC commands. We must allow
+	 * for 3 octets since for MCC frames we use 7 bits + EA in each.
+	 *
+	 * Only test data can possibly be that big.
+	 *
+	 * XXX Should we check this against the MTU?
+	 */
+	if (len < (1 << 7)) {
+		*hdr++ = ((len << 1) & 0xfe) | 0x01;	/* 7 bits, EA = 1 */
+	} else if (len < (1 << 14)) {
+		*hdr++ = ((len << 1) & 0xfe);		/* 7 bits, EA = 0 */
+		*hdr++ = ((len >> 6) & 0xfe) | 0x01;	/* 7 bits, EA = 1 */
+	} else if (len < (1 << 15)) {
+		*hdr++ = ((len << 1) & 0xfe);		/* 7 bits, EA = 0 */
+		*hdr++ = ((len >> 6) & 0xfe);		/* 7 bits, EA = 0 */
+		*hdr++ = ((len >> 13) & 0x02) | 0x01;	/* 1 bit,  EA = 1 */
+	} else {
+		DPRINTF("incredible length! (%d)\n", len);
+		m_freem(m);
+		return EMSGSIZE;
+	}
+
+	/*
+	 * add command data (to same mbuf if possible)
+	 */
+	hlen = hdr - mtod(m, uint8_t *);
+
+	if (len > 0) {
+		m->m_pkthdr.len = m->m_len = MHLEN;
+		m_copyback(m, hlen, len, data);
+		if (m->m_pkthdr.len != max(MHLEN, hlen + len)) {
+			m_freem(m);
+			return ENOMEM;
+		}
+	}
+
+	m->m_pkthdr.len = hlen + len;
+	m->m_len = min(MHLEN, m->m_pkthdr.len);
+
+	DPRINTFN(5, "%s type %2.2x len %d\n",
+		(cr ? "command" : "response"), type, m->m_pkthdr.len);
+
+	return rfcomm_session_send_uih(rs, NULL, 0, m);
+}